Well I put one on, based on information I found on driveaccord.net where several guys put them on new cars and were collecting oil in the cans.
Also, while I had the head off of mine I took it to the machine shop where they checked it over and said all was good – 105K on the clock and A-OK. I therefore think the car is not poorly maintained or worn out. Fumes from the crankcase are normal, and this is why the manufacturer puts a vent hose from there to the intake.
I purchased one that has a clear tube up the side so you can see how much is in the can. After several months there is now maybe an inch of oil in there (it is slightly smaller than a soda can), and the oil is clean.
Based on this experience I think this is a good way to keep your intake from getting gunked up, and pushing more burned oil fumes into your catalytic converter.
This all applies only if you have a car that you think you will drive for a long long time.